Diagnostic system for a battery system

ABSTRACT

A diagnostic system for a battery system having a battery module electrically coupled to a contactor is provided. The battery module has first, second, and third battery cells. The diagnostic system includes a first microcontroller that transitions the contactor to an open operational state if the first battery cell analog overvoltage flag is equal to the first battery cell analog overvoltage flag value. The first microcontroller further transitions the contactor to the open operational state if the first battery cell comparator overvoltage flag is equal to the first battery cell comparator overvoltage flag value.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/354,847 filed on Jun. 27, 2016, the entire contents of which arehereby incorporated by reference herein.

BACKGROUND

The inventor herein has recognized a need for a diagnostic system for abattery system that utilizes battery cell analog overvoltage flags andbattery cell comparator flags to determine when a contactor electricallycoupled to a battery module is to be transitioned to an open operationalstate.

In particular, the inventor has recognized that it would be advantageousto have a diagnostic system that utilizes two independent types of flags(e.g., battery cell analog overvoltage flags and battery cell comparatorovervoltage flags) that can be set to fault values, based on a firstthreshold voltage value and a magnitude of a voltage comparatorthreshold voltage, respectively, that are different from one another—todetermine when a contactor is to be transitioned to an open operationalstate. As a result, the diagnostic system has diagnostic diversity andcan command the contactor to open when a battery cell analog overvoltageflag indicates an output voltage value of a battery cell in the batterymodule is greater than a first threshold voltage value, or when abattery cell comparator overvoltage flag indicates that an outputvoltage of a battery cell in the battery module is greater than amagnitude of a voltage comparator threshold voltage, or both.

SUMMARY

A diagnostic system for a battery system in accordance with an exemplaryembodiment is provided. The battery system has a battery moduleelectrically coupled to a contactor. The battery module has first,second, and third battery cells. The diagnostic system includes a firstmicrocontroller that obtains a first initialization value and first,second, and third battery cell analog overvoltage flag values from amemory device. The first, second, and third analog overvoltage flagvalues are associated with the first, second, and third battery cells,respectively. The first microcontroller further obtains a secondinitialization value and first, second, and third battery cellcomparator overvoltage flag values from the memory device. The first,second, and third battery cell comparator overvoltage flag values areassociated with the first, second, and third battery cells,respectively. The first microcontroller initializes each of first,second, and third battery cell analog overvoltage flags to the firstinitialization value. The first microcontroller receives first, second,and third output voltage values from a second microcontroller. Thefirst, second, and third output voltage values correspond to first,second, and third output voltages, respectively, from the first, second,and third battery cells, respectively. The first microcontroller setsthe first battery cell analog overvoltage flag equal to the firstbattery cell analog overvoltage flag value if the first output voltagevalue is greater than a first threshold voltage value. The firstmicrocontroller sets the second battery cell analog overvoltage flagequal to the second battery cell analog overvoltage flag value if thesecond output voltage value is greater than the first threshold voltagevalue. The first microcontroller sets the third battery cell analogovervoltage flag equal to the third battery cell analog overvoltage flagvalue if the third output voltage value is greater than the firstthreshold voltage value. The first microcontroller transitions thecontactor to an open operational state if the first battery cell analogovervoltage flag is equal to the first battery cell analog overvoltageflag value or the second battery cell analog overvoltage flag equal tothe second battery cell analog overvoltage flag value or the thirdbattery cell analog overvoltage flag equal to the third battery cellanalog overvoltage flag value. The first microcontroller initializeseach of first, second, and third battery cell comparator overvoltageflags to the second initialization value. The first microcontrollerreceives first, second, and third comparator bits from the secondmicrocontroller. The first comparator bit has a first fault value if thefirst output voltage is greater than a voltage comparator thresholdvoltage. The second comparator bit has the first fault value if thesecond output voltage is greater than the voltage comparator thresholdvoltage. The third comparator bit has the first fault value if the thirdoutput voltage is greater than voltage comparator threshold voltage. Thevoltage comparator threshold voltage has a magnitude that is greaterthan the first threshold voltage value. The first microcontroller setsthe first battery cell comparator overvoltage flag equal to the firstbattery cell comparator overvoltage flag value if the first comparatorbit is equal to the first fault value. The first microcontroller setsthe second battery cell comparator overvoltage flag equal to the secondbattery cell comparator overvoltage flag value if the second comparatorbit is equal to the first fault value. The first microcontroller setsthe third battery cell comparator overvoltage flag equal to the thirdbattery cell comparator overvoltage flag value if the third comparatorbit is equal to the first fault value. The first microcontrollertransitions the contactor to the open operational state if the firstbattery cell comparator overvoltage flag is equal to the first batterycell comparator overvoltage flag value or the second battery cellcomparator overvoltage flag is equal to the second battery cellcomparator overvoltage flag value or the third battery cell comparatorovervoltage flag is equal to the third battery cell comparatorovervoltage flag value.

A diagnostic system for a battery system in accordance with anotherexemplary embodiment is provided. The battery system has first, second,third and fourth battery modules electrically coupled in series to acontactor. The first battery module has at least a first battery cell,and the second battery module has at least a first battery cell. Thethird battery module has at least a first battery cell, and the fourthbattery module has at least a first battery cell. The diagnostic systemincludes a memory device having first, second, and third tables storedtherein. The first table has first, second, third and fourth batterymodule numbers associated with the first, second, third and fourthbattery modules, respectively. The first, second, and third batterymodule numbers have a Hamming distance of at least two from each other.The diagnostic system includes a first microcontroller that reads thefirst table stored in the memory device to obtain the first, second,third and fourth battery module numbers. The first microcontroller setsa first battery cell analog overvoltage flag associated with the firstbattery cell in the first battery module to a first value. The firstmicrocontroller stores the first battery cell analog overvoltage flagand the first battery module number in a first record in the secondtable. The first microcontroller sets a first battery cell comparatorovervoltage flag associated with the first battery cell in the firstbattery module to a second value. The first microcontroller stores thefirst battery cell comparator overvoltage flag and the first batterymodule number in a first record in the third table.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a vehicle having a battery system, an electricmotor, and a diagnostic system in accordance with an exemplaryembodiment;

FIG. 2 is a table of battery cell analog overvoltage flag valuesutilized by the diagnostic system of FIG. 1;

FIG. 3 is a table of battery cell comparator overvoltage flag valuesutilized by the diagnostic system of FIG. 1;

FIG. 4 is a table of battery module numbers associated with first,second, third, and fourth battery modules, that are utilized by thediagnostic system of FIG. 1;

FIG. 5 is a first table of exemplary stored diagnostic informationgenerated by the diagnostic system of FIG. 1;

FIG. 6 is a second table of exemplary stored diagnostic informationgenerated by the diagnostic system of FIG. 1;

FIGS. 7-9 are flowcharts of a first diagnostic method utilized by thediagnostic system of FIG. 1; and

FIGS. 10-11 are flowcharts of a second diagnostic method utilized by thediagnostic system of FIG. 1.

DETAILED DESCRIPTION

Referring to FIG. 1, a vehicle 10 includes a battery system 20, a DC-ACinverter 22, an electric motor 24, and a diagnostic system 26 inaccordance with an exemplary embodiment.

An advantage of the diagnostic system 26 is that the system utilizes twoindependent types of flags (e.g., battery cell analog overvoltage flagsand battery cell comparator overvoltage flags) that can be set to faultvalues, based on a first threshold voltage value and a magnitude of avoltage comparator threshold voltage, respectively, that are differentfrom one another—to determine when a contactor is to be transitioned toan open operational state. As a result, the diagnostic system 26 hasdiagnostic diversity and can command the contactor to open when abattery cell analog overvoltage flag indicates an output voltage valueof a battery cell in the battery module is greater than a firstthreshold voltage value, or when a battery cell comparator overvoltageflag indicates that an output voltage of a battery cell in the batterymodule is greater than a magnitude of a voltage comparator thresholdvoltage, or both.

The battery system 20 provides a DC voltage to the DC-AC inverter 22.The battery system 20 includes battery modules 40, 42, 44, 46,contactors 52, 54, and voltage drivers, 60, 62, 64, 66.

The battery module 40 has first, second, and third battery cells 100,102, 104 electrically coupled in series with one another between apositive battery module terminal 106 and a negative battery moduleterminal 108. In an exemplary embodiment, the first, second, and thirdbattery cells 100, 102, 104 are pouch-type lithium-ion battery cells. Ofcourse, in an alternative embodiment, each of the first, second, andthird battery cells 100, 102, 104 could comprise another type of batterycell such as nickel-cadmium battery cell, a nickel-metal-hydride batterycell, or a lead acid battery cell for example. The first battery cell100 has a positive terminal 120 and a negative terminal 122. Also, thesecond battery cell 102 has a positive terminal 130 and a negativeterminal 132. Further, the third battery cell 104 has a positiveterminal 140 and a negative terminal 142. The positive terminal 120 ofthe first battery cell 100 is coupled to the positive battery moduleterminal 106. The negative terminal 122 of the first battery cell 100 iscoupled to the positive terminal 130 of the second battery cell 102. Thenegative terminal 132 of the second battery cell 102 is coupled to thepositive terminal 140 of the third battery cell 104. The negativeterminal 142 of the third battery cell 104 is coupled to the negativebattery module terminal 108. The negative battery module terminal 108 iselectrically coupled to the positive battery module terminal 206 of thebattery module 42. In an alternative embodiment, the battery module 40could have a plurality of additional battery cells electrically coupledto one another in series with the first, second, and third battery cells100, 102, 104, or comprise only a single battery cell.

The battery module 42 has first, second, and third battery cells 200,202, 204 electrically coupled in series with one another between apositive battery module terminal 206 and a negative battery moduleterminal 208. In an exemplary embodiment, the first, second, and thirdbattery cells 200, 202, 204 are pouch-type lithium-ion battery cells. Ofcourse, in an alternative embodiment, each of the first, second, andthird battery cells 200, 202, 204 could comprise another type of batterycell such as nickel-cadmium battery cell, a nickel-metal-hydride batterycell, or a lead acid battery cell for example. The first battery cell200 has a positive terminal 220 and a negative terminal 222. Further,the second battery cell 202 has a positive terminal 230 and a negativeterminal 232. Further, the third battery cell 204 has a positiveterminal 240 and a negative terminal 242. The positive terminal 220 ofthe first battery cell 200 is coupled to the positive battery moduleterminal 206. The negative terminal 222 of the first battery cell 200 iscoupled to the positive terminal 230 of the second battery cell 202. Thenegative terminal 232 of the second battery cell 202 is coupled to thepositive terminal 240 of the third battery cell 204. The negativeterminal 242 of the third battery cell 204 is coupled to the negativebattery module terminal 208. Further, the negative battery moduleterminal 208 is electrically coupled to the positive battery moduleterminal 306 of the battery module 44. In an alternative embodiment, thebattery module 42 could have a plurality of additional battery cellselectrically coupled to one another in series with the first, second,and third battery cells 200, 202, 204, or comprise only a single batterycell.

The battery module 44 has first, second, and third battery cells 300,302, 304 that are electrically coupled in series with one anotherbetween a positive battery module terminal 306 and a negative batterymodule terminal 308. In an exemplary embodiment, the first, second, andthird battery cells 300, 302, 304 are pouch-type lithium-ion batterycells. Of course, in an alternative embodiment, each of the first,second, and third battery cells 300, 302, 304 could comprise anothertype of battery cell such as nickel-cadmium battery cell, anickel-metal-hydride battery cell, or a lead acid battery cell forexample. The first battery cell 300 has a positive terminal 320 and anegative terminal 322. Further, the second battery cell 302 has apositive terminal 330 and a negative terminal 332. Further, the thirdbattery cell 304 has a positive terminal 340 and a negative terminal342. The positive terminal 320 of the first battery cell 300 is coupledto the positive battery module terminal 306. The negative terminal 322of the first battery cell 300 is coupled to the positive terminal 330 ofthe second battery cell 302. The negative terminal 332 of the secondbattery cell 302 is coupled to the positive terminal 340 of the thirdbattery cell 304. The negative terminal 342 of the third battery cell304 is coupled to the negative battery module terminal 308. Further, thenegative battery module terminal 308 is electrically coupled to thepositive battery module terminal 406 of the battery module 46. In analternative embodiment, the battery module 44 could have a plurality ofadditional battery cells electrically coupled to one another in serieswith the first, second, and third battery cells 300, 302, 304, orcomprise only a single battery cell.

The battery module 46 has first, second, and third battery cells 400,402, 404 electrically coupled in series with one another between apositive battery module terminal 406 and a negative battery moduleterminal 408. In an exemplary embodiment, the first, second, and thirdbattery cells 400, 402, 404 are pouch-type lithium-ion battery cells. Ofcourse, in an alternative embodiment, each of the first, second, andthird battery cells 400, 402, 404 could comprise another type of batterycell such as nickel-cadmium battery cell, a nickel-metal-hydride batterycell, or a lead acid battery cell for example. The first battery cell400 has a positive terminal 420 and a negative terminal 422. Further,the second battery cell 402 has a positive terminal 430 and a negativeterminal 432. Further, the third battery cell 404 has a positiveterminal 440 and a negative terminal 442. The positive terminal 420 ofthe first battery cell 400 is coupled to the positive battery moduleterminal 406. The negative terminal 422 of the first battery cell 400 iscoupled to the positive terminal 430 of the second battery cell 402. Thenegative terminal 432 of the second battery cell 402 is coupled to thepositive terminal 440 of the third battery cell 404. The negativeterminal 442 of the third battery cell 404 is coupled to the negativebattery module terminal 408. In an alternative embodiment, the batterymodule 46 could have a plurality of additional battery cellselectrically coupled to one another in series with the first, second,and third battery cells 400, 402, 404, or comprise only a single batterycell.

The contactor 52 is electrically coupled in series between the positivebattery module terminal 106 and the DC-AC inverter 22. The contactor 52includes a contactor coil 500 and a contact 502. When the firstmicrocontroller 600 generates first and second control signals that arereceived by the voltage drivers 60, 62, respectively, the voltagedrivers 60, 62, energize the contactor coil 500, which moves the contact502 to a closed operational state. Alternately, when the firstmicrocontroller 600 stops generating the first and second controlsignals, the voltage drivers 60, 62 de-energize the contactor coil 500,which moves the contact 502 to an open operational state.

The contactor 54 is electrically coupled in series between the negativebattery module terminal 408 and the DC-AC inverter 22. The contactor 54includes a contactor coil 510 and a contact 512. When the firstmicrocontroller 600 generates third and fourth control signals that arereceived by the voltage drivers 64, 66, respectively, the voltagedrivers 64, 66, energize the contactor coil 510, which moves the contact512 to a closed operational state. Alternately, when the firstmicrocontroller 600 stops generating the third and fourth controlsignals, the voltage drivers 64, 66 de-energize the contactor coil 510,which moves the contact 512 to an open operational state.

The DC-AC inverter 22 is electrically coupled to and between thecontactors 52, 54, and provides AC power to the electric motor 24 viathe electrical lines 530, 532, 534, only when the contactors 52, 54 eachhave a closed operational state.

The diagnostic system 26 includes a first microcontroller 600, a secondmicrocontroller 602, a communication bus 604, and a fault line 606.

The first microcontroller 600 includes a microprocessor 630, a memorydevice 632, and an analog-to-digital converter (ADC) 633. Themicroprocessor 630 operably communicates with the memory device 632 andthe analog-to-digital converter 633. Further, the microprocessor 630operably communicates with the microprocessor 650 of the secondmicrocontroller 602 via the communication bus 604, and the fault line606 which is electrically coupled to the analog-to-digital converter633. The microprocessor 630 utilizes software instructions stored in thememory device 632 to implement at least in part the diagnostic stepsdescribed hereinafter, based on data and values received from the secondmicrocontroller 602, as will be described in greater detail below.

The second microcontroller 602 includes a microprocessor 650, a memorydevice 652, an analog-to-digital converter (ADC) 660, and voltagecomparators 700, 702, 704, 706, 708, 710, 720, 722, 724, 726, 728, 730.The microprocessor 650 operably communicates with the memory device 652,the analog-to-digital converter 660, and the voltage comparators 700,702, 704, 660, 708, 710, 720, 722, 724, 726, 728, 730. Themicroprocessor 650 utilizes software instructions stored in the memorydevice 652 to implement at least in part the operational steps for thesecond microcontroller 602.

The analog-to-digital converter 660 includes ADC differential channels661, 662, 663, 664, 665, 666, 667, 668, 669, 670, 671, 672, 673, 674,675, 676.

The ADC differential channel 661 has input pins P1, P2 which areelectrically coupled to the positive terminal 120 and the negativeterminal 122, respectively, of the first battery cell 100 to measure anoutput voltage of the first battery cell 100 between the terminals 120,122, and the analog-to-digital converter 660 generates an output voltagevalue based on the measured output voltage.

The ADC differential channel 662 has input pins P3, P4 which areelectrically coupled to the positive terminal 130 and the negativeterminal 132, respectively, of the second battery cell 102 to measure anoutput voltage of the second battery cell 102 between the terminals 130,132, and the analog-to-digital converter 660 generates an output voltagevalue based on the measured output voltage.

The ADC differential channel 663 has input pins P5, P6 which areelectrically coupled to the positive terminal 140 and the negativeterminal 142, respectively, of the third battery cell 104 to measure anoutput voltage of the third battery cell 104 between the terminals 140,142, and the analog-to-digital converter 660 generates an output voltagevalue based on the measured output voltage.

The ADC differential channel 664 has input pins P7, P8 which areelectrically coupled to the positive battery module terminal 106 and anegative battery module terminal 108 to measure a battery module outputvoltage of the battery module 40, and the analog-to-digital converter660 generates a battery module output voltage value based on themeasured battery module output voltage.

The ADC differential channel 665 has input pins P9, P10 which areelectrically coupled to the positive terminal 220 and the negativeterminal 222, respectively, of the first battery cell 200 to measure anoutput voltage of the first battery cell 200 between the terminals 220,222, and the analog-to-digital converter 660 generates an output voltagevalue based on the measured output voltage.

The ADC differential channel 666 has input pins P11, P12 which areelectrically coupled to the positive terminal 230 and the negativeterminal 232, respectively, of the second battery cell 202 to measure anoutput voltage of the second battery cell 202 between the terminals 230,232, and the analog-to-digital converter 660 generates an output voltagevalue based on the measured output voltage.

The ADC differential channel 667 has input pins P13, P14 which areelectrically coupled to the positive terminal 240 and the negativeterminal 242, respectively, of the third battery cell 204 to measure anoutput voltage of the third battery cell 204 between the terminals 240,242, and the analog-to-digital converter 660 generates an output voltagevalue based on the measured output voltage.

The ADC differential channel 668 has input pins P15, P16 which areelectrically coupled to the positive battery module terminal 206 and anegative battery module terminal 208 to measure a battery module outputvoltage of the battery module 42, and the analog-to-digital converter660 generates a battery module output voltage value based on themeasured battery module output voltage.

The ADC differential channel 669 has input pins P17, P18 which areelectrically coupled to the positive terminal 320 and the negativeterminal 322, respectively, of the first battery cell 300 to measure anoutput voltage of the first battery cell 300 between the terminals 320,322, and the analog-to-digital converter 660 generates an output voltagevalue based on the measured output voltage.

The ADC differential channel 670 has input pins P19, P20 which areelectrically coupled to the positive terminal 330 and the negativeterminal 332, respectively, of the second battery cell 302 to measure anoutput voltage of the second battery cell 302 between the terminals 330,332, and the analog-to-digital converter 660 generates an output voltagevalue based on the measured output voltage.

The ADC differential channel 671 has input pins P21, P22 which areelectrically coupled to the positive terminal 340 and the negativeterminal 342, respectively, of the third battery cell 304 to measure anoutput voltage of the third battery cell 304 between the terminals 340,342, and the analog-to-digital converter 660 generates an output voltagevalue based on the measured output voltage.

The ADC differential channel 672 has input pins P23, P24 which areelectrically coupled to the positive battery module terminal 306 and anegative battery module terminal 308 to measure a battery module outputvoltage of the battery module 44, and the analog-to-digital converter660 generates a battery module output voltage value based on themeasured battery module output voltage.

The ADC differential channel 673 has input pins P25, P26 which areelectrically coupled to the positive terminal 420 and the negativeterminal 422, respectively, of the first battery cell 400 to measure anoutput voltage of the first battery cell 400 between the terminals 420,422, and the analog-to-digital converter 660 generates an output voltagevalue based on the measured output voltage.

The ADC differential channel 674 has input pins P27, P28 which areelectrically coupled to the positive terminal 430 and the negativeterminal 432, respectively, of the second battery cell 402 to measure anoutput voltage of the second battery cell 402 between the terminals 430,432, and the analog-to-digital converter 660 generates an output voltagevalue based on the measured output voltage.

The ADC differential channel 675 has input pins P29, P30 which areelectrically coupled to the positive terminal 440 and the negativeterminal 442, respectively, of the third battery cell 404 to measure anoutput voltage of the third battery cell 404 between the terminals 440,442, and the analog-to-digital converter 660 generates an output voltagevalue based on the measured output voltage.

The ADC differential channel 676 has input pins P31, P32 which areelectrically coupled to the positive battery module terminal 406 and anegative battery module terminal 408 to measure a battery module outputvoltage of the battery module 46, and the analog-to-digital converter660 generates a battery module output voltage value based on themeasured battery module output voltage.

The voltage comparator 700 is electrically coupled to the input pins P1,P2 of the ADC differential channel 661, and compares the output voltage(between input pins P1, P2) of the first battery cell 100 to a voltagecomparator threshold voltage. If the output voltage of the first batterycell 100 is greater than the voltage comparator threshold voltageindicating a cell overvoltage condition, the voltage comparator 700 setsan associated comparator output bit to a binary “1” value (i.e., a faultvalue). Otherwise, the voltage comparator 700 sets the associatedcomparator output bit to a binary “0” value.

The voltage comparator 702 is electrically coupled to the input pins P3,P4 of the ADC differential channel 662, and compares the output voltage(between input pins P3, P4) of the second battery cell 102 to thevoltage comparator threshold voltage. If the output voltage of thesecond battery cell 102 is greater than the voltage comparator thresholdvoltage indicating a cell overvoltage condition, the voltage comparator702 sets an associated comparator output bit to a binary “1” value.Otherwise, the voltage comparator 702 sets the associated comparatoroutput bit to a binary “0” value.

The voltage comparator 704 is electrically coupled to the input pins P5,P6 of the ADC differential channel 663, and compares the output voltage(between input pins P5, P6) of the third battery cell 104 to the voltagecomparator threshold voltage. If the output voltage of the third batterycell 104 is greater than the voltage comparator threshold voltageindicating a cell overvoltage condition, the voltage comparator 704 setsan associated comparator output bit to a binary “1” value. Otherwise,the voltage comparator 704 sets the associated comparator output bit toa binary “0” value.

The voltage comparator 706 is electrically coupled to the input pins P9,P10 of the ADC differential channel 665, and compares the output voltage(between input pins P9, P10) of the first battery cell 200 to thevoltage comparator threshold voltage. If the output voltage of the firstbattery cell 200 is greater than the voltage comparator thresholdvoltage indicating a cell overvoltage condition, the voltage comparator706 sets an associated comparator output bit to a binary “1” value.Otherwise, the voltage comparator 706 sets the associated comparatoroutput bit to a binary “0” value.

The voltage comparator 708 is electrically coupled to the input pinsP11, P12 of the ADC differential channel 666, and compares the outputvoltage (between input pins P11, P12) of the second battery cell 202 tothe voltage comparator threshold voltage. If the output voltage of thesecond battery cell 202 is greater than the voltage comparator thresholdvoltage indicating a cell overvoltage condition, the voltage comparator708 sets an associated comparator output bit to a binary “1” value.Otherwise, the voltage comparator 708 sets the associated comparatoroutput bit to a binary “0” value.

The voltage comparator 710 is electrically coupled to the input pinsP13, P14 of the ADC differential channel 667, and compares the outputvoltage (between input pins P13, P14) of the third battery cell 204 tothe voltage comparator threshold voltage. If the output voltage of thethird battery cell 204 is greater than the voltage comparator thresholdvoltage indicating a cell overvoltage condition, the voltage comparator710 sets an associated comparator output bit to a binary “1” value.Otherwise, the voltage comparator 710 sets the associated comparatoroutput bit to a binary “0” value.

The voltage comparator 720 is electrically coupled to input pins P17,P18 of the ADC differential channel 669, and compares the output voltage(between input pins P17, P18) of the first battery cell 300 to a voltagecomparator threshold voltage. If the output voltage of the first batterycell 300 is greater than the voltage comparator threshold voltageindicating a cell overvoltage condition, the voltage comparator 720 setsan associated comparator output bit to a binary “1” value (i.e., a faultvalue). Otherwise, the voltage comparator 720 sets the associatedcomparator output bit to a binary “0” value.

The voltage comparator 722 is electrically coupled to input pins P19,P20 of the ADC differential channel 670, and compares the output voltage(between input pins P19, P20) of the second battery cell 302 to thevoltage comparator threshold voltage. If the output voltage of thesecond battery cell 302 is greater than the voltage comparator thresholdvoltage indicating a cell overvoltage condition, the voltage comparator722 sets an associated comparator output bit to a binary “1” value.Otherwise, the voltage comparator 722 sets the associated comparatoroutput bit to a binary “0” value.

The voltage comparator 724 is electrically coupled to input pins P21,P22 of the ADC differential channel 671, and compares the output voltage(between input pins P21, P22) of the third battery cell 304 to thevoltage comparator threshold voltage. If the output voltage of the thirdbattery cell 304 is greater than the voltage comparator thresholdvoltage indicating a cell overvoltage condition, the voltage comparator724 sets an associated comparator output bit to a binary “1” value.Otherwise, the voltage comparator 724 sets the associated comparatoroutput bit to a binary “0” value.

The voltage comparator 726 is electrically coupled to input pins P25,P26 of the ADC differential channel 673, and compares the output voltage(between input pins P25, P26) of the first battery cell 400 to thevoltage comparator threshold voltage. If the output voltage of the firstbattery cell 400 is greater than the voltage comparator thresholdvoltage indicating a cell overvoltage condition, the voltage comparator726 sets an associated comparator output bit to a binary “1” value.Otherwise, the voltage comparator 726 sets the associated comparatoroutput bit to a binary “0” value.

The voltage comparator 728 is electrically coupled to input pins P27,P28 of the ADC differential channel 674, and compares the output voltage(between input pins P27, P28) of the second battery cell 402 to thevoltage comparator threshold voltage. If the output voltage of thesecond battery cell 402 is greater than the voltage comparator thresholdvoltage indicating a cell overvoltage condition, the voltage comparator728 sets an associated comparator output bit to a binary “1” value.Otherwise, the voltage comparator 728 sets the associated comparatoroutput bit to a binary “0” value.

The voltage comparator 730 is electrically coupled to input pins P29,P30 of the ADC differential channel 675, and compares the output voltage(between input pins P29, P30) of the third battery cell 404 to thevoltage comparator threshold voltage. If the output voltage of the thirdbattery cell 404 is greater than the voltage comparator thresholdvoltage indicating a cell overvoltage condition, the voltage comparator730 sets an associated comparator output bit to a binary “1” value.Otherwise, the voltage comparator 730 sets the associated comparatoroutput bit to a binary “0” value.

The second microcontroller 602 operably communicates with the firstmicrocontroller 600 utilizing a communication bus 604. Further, thesecond microcontroller 602 sets a fault line 606 from a first fault linevoltage to a second fault line voltage if at least one of the first,second, and third output voltages of the first, second, and thirdbattery cells 100, 102, 104, respectively, of the battery module 40 aregreater than the voltage comparator threshold voltage, or at least oneof the first, second, and third output voltages of the first, second,and third battery cells 200, 202, 204, respectively, of the batterymodule 42 are greater than the voltage comparator threshold voltage, orat least one of the first, second, and third output voltages of thefirst, second, and third battery cells 300, 302, 304, respectively, ofthe battery module 44 are greater than the voltage comparator thresholdvoltage, or at least one of the first, second, and third output voltagesof the first, second, and third battery cells 400, 402, 404,respectively, of the battery module 46 are greater than the voltagecomparator threshold voltage.

Referring to FIGS. 1 and 2, an exemplary table 780 stored in the memorydevice 632 in the first microcontroller 600 is illustrated. The table780 has records 782, 784, 786, 788 therein. The table 780 includesbattery cell analog overvoltage flag values which are associated withthe first, second, and third battery cells 100, 102, 104, respectively,in the battery module 40. It is noted that each of the other batterymodules would have a distinct table with other battery cell analogovervoltage flag values for battery cells in the other battery modules.

The record 782 is associated with the first, second, and third batterycells 100, 102, 104. The record 782 includes an initialization valuewhich is a binary value “111” corresponding to the decimal value of “7.”The first, second, and third battery cell analog overvoltage flagsassociated with the first, second, and third battery cells 100, 102,104, respectively, are initially set equal to the initialization value“111”—which indicates that no overvoltage condition is initiallydetected in the first, second, and third battery cells 100, 102, 104.

The record 784 is associated with the first battery cell 100 in thebattery module 40. The record 784 includes a first battery cell analogovervoltage flag value which is binary value “001” corresponding to thedecimal value of “1.” The first battery cell analog overvoltage flagassociated with the first battery cell 100 is set equal to the firstbattery cell analog overvoltage flag value “001 if an overvoltagecondition (corresponding to the first battery cell 100 having an outputvoltage value greater than a first threshold voltage value) is detectedin the first battery cell 100.

The record 786 is associated with the second battery cell 102 in thebattery module 40. The record 786 includes a second battery cell analogovervoltage flag value which is binary value “100” corresponding to thedecimal value of “4.” The second battery cell analog overvoltage flagassociated with the second battery cell 102 is set equal to the secondbattery cell analog overvoltage flag value “100” if an overvoltagecondition (corresponding to the second battery cell 102 having an outputvoltage value greater than a first threshold voltage value is detectedin the second battery cell 102.

The record 788 is associated with the third battery cell 104 in thebattery module 40. The record 788 includes a third battery cell analogovervoltage flag value which is binary value “010” corresponding to thedecimal value of “2.” The third battery cell analog overvoltage flagassociated with the third battery cell 104 is set equal to the thirdbattery cell analog overvoltage flag value “010” if an overvoltagecondition (corresponding to the third battery cell 104 having an outputvoltage value greater than a first threshold voltage value) is detectedin the third battery cell 104.

It is noted that in table 780, the initialization value and the first,second, third and fourth battery cell analog overvoltage flag valueseach have a Hamming distance of at least two from each other.

Referring to FIG. 3, an exemplary table 800 stored in the memory device632 in the first microcontroller 600 is illustrated. The table 800 hasrecords 802, 804, 806, 808 therein. The table 800 includes battery cellcomparator overvoltage flag values which are associated with the first,second, and third battery cells 100, 102, 104, respectively, in thebattery module 40 are illustrated. It is noted that each of the othermodules would have a distinct table with other battery cell comparatorovervoltage flag values for battery cells in the respective tables.

The record 802 is associated with the first, second, and third batterycells 100, 102, 104. The record 802 includes an initialization valuewhich is a binary value “000” corresponding to the decimal value of “0.”The first, second, and third battery cell comparator overvoltage flagsassociated with the first, second, and third battery cells 100, 102,104, respectively, are initially set equal to the initialization value“000”—which indicates that no overvoltage condition is initiallydetected in the first, second, and third battery cells 100, 102, 104 byvoltage comparators 700, 702, 704, respectively.

The record 804 is associated with the first battery cell 100 in thebattery module 40. The record 804 includes a first battery cellcomparator overvoltage flag value which is binary value “110”corresponding to the decimal value of “6.” The first battery cellcomparator overvoltage flag associated with the first battery cell 100is set equal to the first battery cell comparator overvoltage flag value“110” if an overvoltage condition (corresponding to the first batterycell 100 having an output voltage level greater than the voltagecomparator threshold voltage is detected in the first battery cell 100by the voltage comparator 700.

The record 806 is associated with the second battery cell 102 in thebattery module 40. The record 806 includes a second battery cellcomparator overvoltage flag value which is binary value “011”corresponding to the decimal value of “3.” The second battery cellcomparator overvoltage flag associated with the second battery cell 102is set equal to the second battery cell comparator overvoltage flagvalue “011” if an overvoltage condition (corresponding to the secondbattery cell 102 having an output voltage level greater than the voltagecomparator threshold voltage is detected in the second battery cell 102by the voltage comparator 702.

The record 808 is associated with the third battery cell 104 in thebattery module 40. The record 808 includes a third battery cellcomparator overvoltage flag value which is binary value “101”corresponding to the decimal value of “5.” The third battery cellcomparator overvoltage flag associated with the third battery cell 104is set equal to the third battery cell comparator overvoltage flag value“101” if an overvoltage condition (corresponding to the third batterycell 104 having an output voltage level greater than the voltagecomparator threshold voltage is detected in the third battery cell 104by the voltage comparator 704.

It is noted that in table 800, the initialization value and the first,second, third and fourth battery cell comparator overvoltage flag valueseach have a Hamming distance of at least two from each other. Further,in table 800, the initialization value and the first, second, third andfourth battery cell comparator overvoltage flag values each have aHamming distance of at least two from the initialization value and thefirst, second, third and fourth battery cell analog overvoltage flagvalues in the table 780.

Referring to FIGS. 1 and 4, an exemplary table 830 that is stored in thememory device 632 in the first microcontroller 600 is illustrated. Thetable 830 has records 831, 832, 833, 834 therein. The table 830 includesbattery module numbers which are associated with the first, second,third, and fourth battery modules 40, 42, 44, 46, respectively.

The record 831 has a first battery module number associated with thebattery module 40. In particular, the first battery module number is abinary value “110” corresponding to a decimal value “6.”

The record 832 has a second battery module number associated with thebattery module 42. In particular, the second battery module number is abinary value “001” corresponding to a decimal value “1.”

The record 833 has a third battery module number associated with thebattery module 44. In particular, the third battery module number is abinary value “100” corresponding to a decimal value “4.”

The record 834 has a fourth battery module number associated with thebattery module 46. In particular, the fourth battery module number is abinary value “111” corresponding to a decimal value “7.”

Referring to FIGS. 1 and 5, an exemplary table 860 that is stored in thememory device 632 in the first microcontroller 600 is illustrated. Thetable 860 has records 861, 862, 863, 864, 865, 866, 867, 868, 869, 870,871, 872 associated with battery cells 100, 102, 104, 200, 202, 204,300, 302, 304, 400, 402, 404, respectively, therein. The table 860 isused to stored exemplary battery cell analog overvoltage flags therein.

The record 861 is associated with the first battery cell 100 in thebattery module 40. The record 861 includes a first battery cell analogovervoltage flag which is binary value “001” (defined in table 780)indicating an overvoltage condition in the first battery cell 100, and abattery module number “110” (defined in table 830) associated with thebattery module 40.

The record 862 is associated with the second battery cell 102 in thebattery module 40. The record 862 includes a second battery cell analogovervoltage flag which is binary value “100” indicating an overvoltagecondition in the second battery cell 102, and a battery module number“110” associated with the battery module 40.

The record 863 is associated with the third battery cell 104 in thebattery module 40. The record 863 includes a third battery cell analogovervoltage flag which is binary value “010” indicating an overvoltagecondition in the third battery cell 104, and a battery module number“110” associated with the battery module 40.

The record 864 is associated with the first battery cell 200 in thebattery module 42. The record 864 includes a first battery cell analogovervoltage flag which is binary value “111” indicating anon-overvoltage condition in the first battery cell 200, and a batterymodule number “001” associated with the battery module 42.

The record 865 is associated with the second battery cell 202 in thebattery module 42. The record 865 includes a second battery cell analogovervoltage flag which is binary value “111” indicating anon-overvoltage condition in the second battery cell 202, and a batterymodule number “001” associated with the battery module 42.

The record 866 is associated with the third battery cell 204 in thebattery module 42. The record 866 includes a third battery cell analogovervoltage flag which is binary value “111” indicating anon-overvoltage condition in the third battery cell 204, and a batterymodule number “001” associated with the battery module 42.

The record 867 is associated with the first battery cell 300 in thebattery module 44. The record 867 includes a first battery cell analogovervoltage flag which is binary value “111” indicating anon-overvoltage condition in the first battery cell 300, and a batterymodule number “100” associated with the battery module 44.

The record 868 is associated with the second battery cell 302 in thebattery module 44. The record 868 includes a second battery cell analogovervoltage flag which is binary value “111” indicating anon-overvoltage condition in the second battery cell 302, and a batterymodule number “100” associated with the battery module 44.

The record 869 is associated with the third battery cell 304 in thebattery module 44. The record 869 includes a third battery cell analogovervoltage flag which is binary value “111” indicating anon-overvoltage condition in the third battery cell 304, and a batterymodule number “100” associated with the battery module 44.

The record 870 is associated with the first battery cell 400 in thebattery module 46. The record 870 includes a first battery cell analogovervoltage flag which is binary value “111” indicating anon-overvoltage condition in the first battery cell 400, and a batterymodule number “111” associated with the battery module 46.

The record 871 is associated with the second battery cell 402 in thebattery module 46. The record 871 includes a second battery cell analogovervoltage flag which is binary value “111” indicating anon-overvoltage condition in the second battery cell 402, and a batterymodule number “111” associated with the battery module 46.

The record 872 is associated with the third battery cell 404 in thebattery module 46. The record 872 includes a third battery cell analogovervoltage flag which is binary value “111” indicating anon-overvoltage condition in the third battery cell 404, and a batterymodule number “111” associated with the battery module 46.

Referring to FIGS. 1 and 6, an exemplary table 900 that is stored in thememory device 632 in the first microcontroller 600 is illustrated. Thetable 900 has records 901, 902, 903, 904, 905, 906, 907, 908, 909, 910,911, 912 associated with battery cells 100, 102, 104, 200, 202, 204,300, 302, 304, 400, 402, 404, respectively, therein. The table 900 isused to stored exemplary battery cell comparator overvoltage flagstherein.

The record 901 is associated with the first battery cell 100 in thebattery module 40. The record 901 includes a battery module number “110”(defined in table 830) associated with the battery module 40, and afirst battery cell comparator overvoltage flag which is binary value“011” (defined in table 800) indicating an overvoltage condition in thefirst battery cell 100.

The record 902 is associated with the second battery cell 102 in thebattery module 40. The record 902 includes a battery module number “110”associated with the battery module 40, and a second battery cellcomparator overvoltage flag which is binary value “101” indicating anovervoltage condition in the second battery cell 102.

The record 903 is associated with the third battery cell 104 in thebattery module 40. The record 903 includes a battery module number “110”associated with the battery module 40, and a third battery cellcomparator overvoltage flag which is binary value “110” indicating anovervoltage condition in the third battery cell 104.

The record 904 is associated with the first battery cell 200 in thebattery module 42. The record 904 includes a battery module number “001”associated with the battery module 42, and a first battery cellcomparator overvoltage flag which is binary value “000” indicating anon-overvoltage condition in the first battery cell 200.

The record 905 is associated with the second battery cell 202 in thebattery module 42. The record 905 includes a battery module number “001”associated with the battery module 42, and a second battery cellcomparator overvoltage flag which is binary value “000” indicating anon-overvoltage condition in the second battery cell 202.

The record 906 is associated with the third battery cell 204 in thebattery module 42. The record 906 includes a battery module number “001”associated with the battery module 42, and a third battery cellcomparator overvoltage flag which is binary value “000” indicating anon-overvoltage overvoltage condition in the third battery cell 204.

The record 907 is associated with the first battery cell 300 in thebattery module 44. The record 907 includes a battery module number “100”associated with the battery module 44, and a first battery cellcomparator overvoltage flag which is binary value “000” indicating anon-overvoltage condition in the first battery cell 300.

The record 908 is associated with the second battery cell 302 in thebattery module 44. The record 908 includes a battery module number “100”associated with the battery module 44, and a second battery cellcomparator overvoltage flag which is binary value “000” indicating anon-overvoltage condition in the second battery cell 302.

The record 909 is associated with the third battery cell 304 in thebattery module 44. The record 909 includes a battery module number “100”associated with the battery module 44, and a third battery cellcomparator overvoltage flag which is binary value “000” indicating anon-overvoltage condition in the third battery cell 304.

The record 910 is associated with the first battery cell 400 in thebattery module 46. The record 910 includes a battery module number “111”associated with the battery module 46, and a first battery cellcomparator overvoltage flag which is binary value “000” indicating anon-overvoltage condition in the first battery cell 400.

The record 911 is associated with the second battery cell 402 in thebattery module 46. The record 911 includes a battery module number “111”associated with the battery module 46, and a second battery cellcomparator overvoltage flag which is binary value “000” indicating anon-overvoltage condition in the second battery cell 402.

The record 912 is associated with the third battery cell 404 in thebattery module 46. The record 912 includes a battery module number “111”associated with the battery module 46, and a third battery cellcomparator overvoltage flag which is binary value “000” indicating anon-overvoltage condition in the third battery cell 404.

Referring to FIGS. 1-3, and 7-9, the diagnostic system 26 implements afirst diagnostic method for the battery module 40 in the battery system20 which will be described in further detail below. In particular, thefirst diagnostic method is utilized to set first, second, and thirdbattery cell analog overvoltage flag values associated with the first,second, and third battery cells 100, 102, 104, respectively, and tofurther set first, second, and third battery cell comparator overvoltageflag values associated with the first, second, and third battery cells100, 102, 104, respectively, in order to determine whether at least oneof the contactors 52, 54 should be transitioned from a closedoperational state to an open operational state. For purposes ofsimplicity, the first diagnostic method will only be discussed withrespect to the first, second, third battery cells 100, 102, 104 andbattery module 40. However it should be understood that the firstdiagnostic method could further be implemented to encompass testing thebattery cells in the other battery modules 42, 44, 46, in order todetermine whether at least one of the contactors 52, 54 should betransitioned from a closed operational state to an open operationalstate. In an exemplary embodiment, the diagnostic system 26 transitionsat least one of the contactors 52, 54 from a closed operational state toan open operational state if any of the battery cells 100, 102, 104 havean overvoltage condition. For example, when the first controller 600transitions the contactor 52 from a closed operational state to an openoperational state in the first diagnostic method, the first controller600 could also simultaneously transition the contactor 54 from a closedoperational state to an open operational state. However, for purposes ofsimplicity, the first diagnostic method will only be discussed withrespect to the contactor 52. Further, it is assumed that prior toimplementing the first diagnostic method that the first microcontroller600 is generating control signals to induce the contactor 52 and thecontactor 54 to each have closed operational states.

At step 940, the first microcontroller 600 reads tables 780, 800 (shownin FIGS. 2 and 3) stored in a memory device 630. The tables 780, 800 areassociated with the battery module 40. The table 780 has a firstinitialization value and first, second, and third battery cell analogovervoltage flag values. The first, second, and third battery cellanalog overvoltage flag values are associated with the first, second,and third battery cells 100, 102, 104, respectively, of the batterymodule 40. The table 800 has a second initialization value and first,second, and third battery cell comparator overvoltage flag values. Thefirst, second, and third battery cell comparator overvoltage flag valuesare associated with first, second, and third battery cells 100, 102,104, respectively, of the battery module 40. After step 940, the methodadvances to step 942.

At step 942, the first microcontroller 600 initializes each of first,second, and third battery cell analog overvoltage flags to the firstinitialization value (e.g., 111 shown in record 782 in FIG. 2). Afterstep 942, the method advances to step 944.

At step 944, the first microcontroller 600 initializes each of first,second, and third battery cell comparator overvoltage flags to thesecond initialization value (e.g., 000 shown in record 802 in FIG. 3).After step 944, the method advances to step 946.

At step 946, the second microcontroller 602 has an analog-to-digitalconverter 660 with first, second, and third analog-to-digital converterdifferential channels 661, 662, 663 measuring first, second, and thirdoutput voltages, respectively, of the first, second, and third batterycells 100, 102, 104, respectively. The analog-to-digital converter 660generates first, second, and third output voltage values based on thefirst, second, and third output voltages, respectively. After step 946,the method advances to step 948.

At step 948, the second microcontroller 602 sends the first, second, andthird output voltage values to the first microcontroller 600 utilizingthe communication bus 604. After step 948, the method advances to step950.

At step 950, the first microcontroller 600 sets the first battery cellanalog overvoltage flag equal to the first battery cell analogovervoltage flag value if the first output voltage value is greater thana first threshold voltage value. After step 950, the method advances tostep 952.

At step 952, the first microcontroller 600 sets the second battery cellanalog overvoltage flag equal to the second battery cell analogovervoltage flag value if the second output voltage value is greaterthan the first threshold voltage value. After step 952, the methodadvances to step 954.

At step 954, the first microcontroller 600 sets the third battery cellanalog overvoltage flag equal to the third battery cell analogovervoltage flag value if the third output voltage value is greater thanthe first threshold voltage value. After step 954, the method advancesto step 956.

At step 956, the first microcontroller 600 transitions the contactor 52to an open operational state if the first battery cell analogovervoltage flag is equal to the first battery cell analog overvoltageflag value or the second battery cell analog overvoltage flag equal tothe second battery cell analog overvoltage flag value or the thirdbattery cell analog overvoltage flag equal to the third battery cellanalog overvoltage flag value. After step 956, the method advances tostep 958.

At step 958, the second microcontroller 602 has first, second, and thirdvoltage comparators 700, 702, 704 that are electrically coupled to thefirst, second, and third battery cells 100, 102, 104. The first, second,and third voltage comparators 700, 702, 704 generate first, second, andthird comparator bits. The first comparator bit is set equal to a firstfault value by the first voltage comparator 700 if the first outputvoltage from the first battery cell is greater than a voltage comparatorthreshold voltage. The second comparator bit is set equal to the firstfault value by the second voltage comparator 702 if the second outputvoltage of the second battery cell is greater than the voltagecomparator threshold voltage. The third comparator is set equal to thefirst fault value by the third voltage comparator 704 if the thirdoutput voltage of the third battery cell is greater than the voltagecomparator threshold voltage. The voltage comparator threshold voltagehas a magnitude that is greater than the first threshold voltage value.After step 958, the method advances to step 960.

At step 960, the second microcontroller 602 sends the first, second, andthird comparator bits to the first microcontroller 600 utilizing thecommunication bus 604. After step 960, the method advances to step 962.

At step 962, the first microcontroller 600 sets the first battery cellcomparator overvoltage flag equal to the first battery cell comparatorovervoltage flag value if the first comparator bit is equal to the firstfault value. After step 962, the method advances to step 964.

At step 964, the first microcontroller 600 sets the second battery cellcomparator overvoltage flag equal to the second battery cell comparatorovervoltage flag value if the second comparator bit is equal to thefirst fault value. After step 964, the method advances to step 966.

At step 966, the first microcontroller 600 sets the third battery cellcomparator overvoltage flag equal to the third battery cell comparatorovervoltage flag value if the third comparator bit is equal to the firstfault value. After step 966, the method advances to step 968.

At step 968, the first microcontroller 600 transitions the contactor 52to the open operational state if the first battery cell comparatorovervoltage flag is equal to the first battery cell comparatorovervoltage flag value or the second battery cell comparator overvoltageflag is equal to the second battery cell comparator overvoltage flagvalue or the third battery cell comparator overvoltage flag is equal tothe third battery cell comparator overvoltage flag value. After step968, the method is exited.

Referring to FIGS. 1, 5, 6 and 10-11, the diagnostic system 26implements a second diagnostic method for the battery modules 40, 42,44, 46 in the battery system 20 which will be described in furtherdetail below. The second diagnostic method is directed to storingbattery cell analog overvoltage flags and associated battery modulenumbers in a table 860 (shown in FIG. 5), and storing batteries cellcomparator overvoltage flags and associated battery module numbers inthe table 900 (shown in FIG. 6). For purposes of simplicity, the seconddiagnostic method will only be discussed with respect to the firstbattery cell in each of the battery modules 40, 42, 44, 46. However itshould be understood that the second diagnostic method could further beimplemented with respect to all of the battery cells in the batterymodules 40, 42, 44, 46. Further it should be understood that the batterycell analog overvoltage flags will be stored in the table 860 after thebattery cell analog overvoltage flags are set to specific values duringdiagnostic overvoltage tests (described in the first diagnostic methodwith respect to module 40) of the battery cells in the battery modules40, 42, 44, 46. Similarly, the battery cell comparator overvoltage flagswill be stored in the table 900 after the battery cell analogovervoltage flags are set to specific values during diagnosticovervoltage tests (described in the first diagnostic method with respectto module 40) of the battery cells in the battery modules 40, 42, 44,46.

At step 980, the first microcontroller 600 reads the table 830 (shown inFIG. 4) stored in the memory device 632 to obtain the first, second,third and fourth battery module numbers that are associated with batterymodules 40, 42, 44, 46, respectively. The first, second, and thirdbattery module numbers have a Hamming distance of at least two from eachother. After step 980, the method advances to step 982.

At step 982, the first microcontroller 600 sets a first battery cellanalog overvoltage flag associated with the first battery cell 100 inthe battery module 40 to a first value (e.g., 001). After step 982, themethod advances to step 984.

At step 984, the first microcontroller 600 stores the first battery cellanalog overvoltage flag and the first battery module number (e.g., 110)in the record 861 in the table 860 stored in the memory device 632.After step 984, the method advances to step 986.

At step 986, the first microcontroller 600 sets a first battery cellcomparator overvoltage flag associated with the first battery cell 100in the battery module 40 to a second value (e.g., 011). After step 986,the method advances to step 988.

At step 988, the first microcontroller 600 stores the first battery cellcomparator overvoltage flag and the first battery module number in therecord 901 in the table 900 stored in the memory device 632. After step988, the method advances to step 990.

At step 990, the first microcontroller 600 sets a second battery cellanalog overvoltage flag associated with the first battery cell 200 inthe battery module 42 to a third value. After step 990, the methodadvances to step 992.

At step 992, the first microcontroller 600 stores the second batterycell analog overvoltage flag and the second battery module number in therecord 864 in the table 860. After step 992, the method advances to step994.

At step 994, the first microcontroller 600 sets a second battery cellcomparator overvoltage flag associated with the first battery cell 200in the battery module 42 to a fourth value. After step 994, the methodadvances to step 996.

At step 996, the first microcontroller 600 stores the second batterycell comparator overvoltage flag and the second battery module number inthe record 904 in the table 900. After step 996, the method advances tostep 998.

At step 998, the first microcontroller 600 sets a third battery cellanalog overvoltage flag associated with the first battery cell 300 inthe battery module 44 to a fifth value. After step 998, the methodadvances to step 1000.

At step 1000, the first microcontroller 600 stores the third batterycell analog overvoltage flag and the third battery module number in therecord 867 in the table 860. After step 1000, the method advances tostep 1002.

At step 1002, the first microcontroller 600 sets a third battery cellcomparator overvoltage flag associated with the first battery cell 300in the battery module 44 to a sixth value. After step 1002, the methodadvances to step 1004.

At step 1004, the first microcontroller 600 stores the third batterycell comparator overvoltage flag and the third battery module number inthe record 907 in the table 900. After step 1004, the method advances tostep 1006.

At step 1006, the first microcontroller 600 sets a fourth battery cellanalog overvoltage flag associated with the first battery cell 400 inthe battery module 46 to a seventh value. After step 1006, the methodadvances to step 1008.

At step 1008, the first microcontroller 600 stores the fourth batterycell analog overvoltage flag and the fourth battery module number in therecord 870 in the table 860. After step 1008, the method advances tostep 1010.

At step 1010, the first microcontroller 600 sets a fifth battery cellanalog overvoltage flag associated with the first battery cell 400 inthe battery module 46 to an eighth value. After step 1010, the methodadvances to step 1012.

At step 1012, the first microcontroller 600 stores the fourth batterycell comparator overvoltage flag and the fourth battery module number inthe record 910 in the table 900. After step 1012, the method is exited.

The above-described methods can be at least partially embodied in theform of one or more memory devices having computer-executableinstructions for practicing the methods. The memory devices can compriseone or more of the following: hard drives, RAM memory, flash memory, andother computer-readable media known to those skilled in the art;wherein, when the computer-executable instructions are loaded into andexecuted by one or more microcontrollers, the microcontrollers become anapparatus programmed to practice the associated steps of the method.Further, for purposes of understanding, when a voltage value correspondsto (or is based on) a voltage, the voltage value is proportional to orequal to a magnitude or a frequency of the voltage.

The diagnostic system described herein provides a substantial advantageover other systems. In particular, an advantage of the diagnostic systemis that the system utilizes two independent types of flags (e.g.,battery cell analog overvoltage flags and battery cell comparatorovervoltage flags) that can be set to fault values, based on a firstthreshold voltage value and a magnitude of a voltage comparatorthreshold voltage, respectively, that are different from one another—todetermine when a contactor is to be transitioned to an open operationalstate. As a result, the diagnostic system has diagnostic diversity andcan command the contactor to open to remove electrical power from a load(e.g., a DC-AC inverter and an electric motor) when a battery cellanalog overvoltage flag indicates an output voltage value of a batterycell in the battery module is greater than a first threshold voltagevalue, or when a battery cell comparator overvoltage flag indicates thatan output voltage of a battery cell in the battery module is greaterthan a magnitude of a voltage comparator threshold voltage, wherein thevoltage comparator threshold voltage has a magnitude that is greaterthan the first threshold voltage value.

While the claimed invention has been described in detail in connectionwith only a limited number of embodiments, it should be readilyunderstood that the invention is not limited to such disclosedembodiments. Rather, the claimed invention can be modified toincorporate any number of variations, alterations, substitutions orequivalent arrangements not heretofore described, but which arecommensurate with the spirit and scope of the invention. Additionally,while various embodiments of the claimed invention have been described,it is to be understood that aspects of the invention may include onlysome of the described embodiments. Accordingly, the claimed invention isnot to be seen as limited by the foregoing description.

What is claimed is:
 1. A diagnostic system for a battery system having abattery module electrically coupled to a contactor, the battery modulehaving a first battery cell, comprising: a first microcontrollerinitializing a first battery cell analog overvoltage flag associatedwith the first battery cell to a first initialization value; the firstmicrocontroller receiving a first output voltage value from a secondmicrocontroller that corresponds to a first output voltage from thefirst battery cell; the first microcontroller setting the first batterycell analog overvoltage flag equal to a first battery cell analogovervoltage flag value if the first output voltage value is greater thana first threshold voltage value; the first microcontroller transitioningthe contactor to an open operational state if the first battery cellanalog overvoltage flag is equal to the first battery cell analogovervoltage flag value; the first microcontroller initializing a batterycell comparator overvoltage flag to the second initialization value; thefirst microcontroller receiving a first comparator bit, from the secondmicrocontroller; the first comparator bit having a first fault value ifthe first output voltage is greater than a voltage comparator thresholdvoltage; the first microcontroller setting the first battery cellcomparator overvoltage flag equal to the first battery cell comparatorovervoltage flag value if the first comparator bit is equal to the firstfault value; and the first microcontroller transitioning the contactorto the open operational state if the first battery cell comparatorovervoltage flag is equal to the first battery cell comparatorovervoltage flag value.
 2. The diagnostic system of claim 1, wherein thefirst microcontroller obtains the first initialization value and thefirst battery cell analog overvoltage flag value by reading a firsttable stored in the memory device, the first table being associated withthe battery module; the first table having the first initializationvalue and the first battery cell analog overvoltage flag value therein.3. The diagnostic system of claim 2, wherein the first microcontrollerobtains the second initialization value and the first battery cellcomparator overvoltage flag value by reading a second table stored inthe memory device; the second table being associated with the batterymodule; the second table having the second initialization value and thefirst battery cell comparator overvoltage flag value therein.
 4. Thediagnostic system of claim 1, wherein the first initialization value andthe first battery cell analog overvoltage flag value each have a Hammingdistance of at least two from each other; and the second initializationvalue and the first battery cell comparator overvoltage flag value eachhave a Hamming distance of at least two from each other.
 5. Thediagnostic system of claim 4, wherein each of the first initializationvalue and the first battery cell analog overvoltage flag value have theHamming distance of at least two from each of the second initializationvalue and the first battery cell comparator overvoltage flag value. 6.The diagnostic system of claim 1, wherein: the second microcontrollerincludes an analog-to-digital converter with a first analog-to-digitalconverter differential channel measuring the first output voltage of thefirst battery cell; the analog-to-digital converter generating the firstoutput voltage value based on the first output voltage.
 7. Thediagnostic system of claim 6, wherein: the second microcontrolleroperably communicates with the first microcontroller utilizing acommunication bus; and the second microcontroller sending the firstoutput voltage value to the first microcontroller utilizing thecommunication bus.
 8. The diagnostic system of claim 7, wherein thesecond microcontroller further includes a first voltage comparatortherein which is electrically coupled to the first battery cell; thefirst voltage comparator setting the first comparator bit equal to thefirst fault value if the first output voltage of the first battery cellis greater than the voltage comparator threshold voltage; and the secondmicrocontroller sending the first comparator bit to the firstmicrocontroller utilizing the communication bus.
 9. The diagnosticsystem of claim 1, wherein the battery module further includes secondand third battery cells: the first microcontroller initializing each ofsecond and third battery cell analog overvoltage flags associated withthe second and third battery cells, respectively, to the firstinitialization value; the first microcontroller receiving second andthird output voltage values from the second microcontroller, the secondand third output voltage values corresponding to second and third outputvoltages, respectively, from the second and third battery cells,respectively; the first microcontroller setting the second battery cellanalog overvoltage flag equal to a second battery cell analogovervoltage flag value if the second output voltage value is greaterthan the first threshold voltage value; the first microcontrollersetting the third battery cell analog overvoltage flag equal to a thirdbattery cell analog overvoltage flag value if the third output voltagevalue is greater than the first threshold voltage value; and the firstmicrocontroller transitioning the contactor to the open operationalstate if the second battery cell analog overvoltage flag is equal to thesecond battery cell analog overvoltage flag value or the third batterycell analog overvoltage flag is equal to the third battery cell analogovervoltage flag value.
 10. The diagnostic system of claim 9, wherein:the first microcontroller initializing each of second and third batterycell comparator overvoltage flags to the second initialization value;the first microcontroller receiving second and third comparator bitsfrom the second microcontroller; the second comparator bit having thefirst fault value if the second output voltage is greater than thevoltage comparator threshold voltage; the third comparator bit havingthe first fault value if the third output voltage is greater thanvoltage comparator threshold voltage; the voltage comparator thresholdvoltage having a magnitude that is greater than the first thresholdvoltage value; the first microcontroller setting the second battery cellcomparator overvoltage flag equal to a second battery cell comparatorovervoltage flag value if the second comparator bit is equal to thefirst fault value; the first microcontroller setting the third batterycell comparator overvoltage flag equal to a third battery cellcomparator overvoltage flag value if the third comparator bit is equalto the first fault value; and the first microcontroller transitioningthe contactor to the open operational state if the second battery cellcomparator overvoltage flag is equal to the second battery cellcomparator overvoltage flag value or the third battery cell comparatorovervoltage flag is equal to the third battery cell comparatorovervoltage flag value.
 11. A diagnostic system for a battery systemhaving first and second battery modules electrically coupled in seriesto a contactor, the first battery module having at least a first batterycell; the second battery module having at least a first battery cell,comprising: a memory device having first, second, and third tablesstored therein; the first table having first and second battery modulenumbers associated with the first and second battery modules,respectively; the first and second battery module numbers having aHamming distance of at least two from each other; a firstmicrocontroller reading the first table stored in the memory device toobtain the first and second battery module numbers; the firstmicrocontroller setting a first battery cell analog overvoltage flagassociated with the first battery cell in the first battery module to afirst value; the first microcontroller storing the first battery cellanalog overvoltage flag and the first battery module number in a firstrecord in the second table; the first microcontroller setting a firstbattery cell comparator overvoltage flag associated with the firstbattery cell in the first battery module to a second value; the firstmicrocontroller storing the first battery cell comparator overvoltageflag and the first battery module number in a first record in the thirdtable.
 12. The diagnostic system of claim 11, wherein the first recordin the second table has the first battery module number appended to anend of the first battery cell analog overvoltage flag.
 13. Thediagnostic system of claim 12, wherein the first record in the thirdtable has the first battery cell comparator overvoltage flag appended toan end of the first battery module number.
 14. The diagnostic system ofclaim 11, wherein: the first microcontroller setting a second batterycell analog overvoltage flag associated with the first battery cell inthe second battery module to a third value; the first microcontrollerstoring the second battery cell analog overvoltage flag and the secondbattery module number in a second record in the second table; the firstmicrocontroller setting a second battery cell comparator overvoltageflag associated with the first battery cell in the second battery moduleto a fourth value; and the first microcontroller storing the secondbattery cell comparator overvoltage flag and the second battery modulenumber in a second record in the third table.
 15. The diagnostic systemof claim 14, wherein the battery system includes third and fourthbattery modules electrically coupled in series to the contactor, thethird battery module having at least a first battery cell, the fourthbattery module having at least a first battery cell, comprising: thefirst table having third and fourth battery module numbers associatedwith the third and fourth battery modules, respectively; the firstmicrocontroller reading the first table stored in the memory device toobtain the third and fourth battery module numbers; the firstmicrocontroller setting a third battery cell analog overvoltage flagassociated with the first battery cell in the third battery module to afifth value; the first microcontroller storing the third battery cellanalog overvoltage flag and the third battery module number in a thirdrecord in the second table; the first microcontroller setting a thirdbattery cell comparator overvoltage flag associated with the firstbattery cell in the third battery module to a sixth value; and the firstmicrocontroller storing the third battery cell comparator overvoltageflag and the third battery module number in a third record in the thirdtable.
 16. The diagnostic system of claim 15, wherein: the firstmicrocontroller setting a fourth battery cell analog overvoltage flagassociated with the first battery cell in the fourth battery module to aseventh value; the first microcontroller storing the fourth battery cellanalog overvoltage flag and the fourth battery module number in a fourthrecord in the second table; the first microcontroller setting a fourthbattery cell comparator overvoltage flag associated with the firstbattery cell in the fourth battery module to an eighth value; and thefirst microcontroller storing the fourth battery cell comparatorovervoltage flag and the fourth battery module number in a fourth recordin the third table.